src/tools/clippy/clippy_lints/src/methods/filetype_is_file.rs

   1 use clippy_utils::diagnostics::span_lint_and_help;
   2 use clippy_utils::get_parent_expr;
   3 use clippy_utils::ty::is_type_diagnostic_item;
   4 use if_chain::if_chain;
   5 use rustc_hir as hir;
   6 use rustc_lint::LateContext;
   7 use rustc_span::source_map::Span;
   8 use rustc_span::sym;
   9
  10 use super::FILETYPE_IS_FILE;
  11
  12 pub(super) fn check(cx: &LateContext<'_>, expr: &hir::Expr<'_>, recv: &hir::Expr<'_>) {
  13     let ty = cx.typeck_results().expr_ty(recv);
  14
  15     if !is_type_diagnostic_item(cx, ty, sym::FileType) {
  16         return;
  17     }
  18
  19     let span: Span;
  20     let verb: &str;
  21     let lint_unary: &str;
  22     let help_unary: &str;
  23     if_chain! {
  24         if let Some(parent) = get_parent_expr(cx, expr);
  25         if let hir::ExprKind::Unary(op, _) = parent.kind;
  26         if op == hir::UnOp::Not;
  27         then {
  28             lint_unary = "!";
  29             verb = "denies";
  30             help_unary = "";
  31             span = parent.span;
  32         } else {
  33             lint_unary = "";
  34             verb = "covers";
  35             help_unary = "!";
  36             span = expr.span;
  37         }
  38     }
  39     let lint_msg = format!("`{lint_unary}FileType::is_file()` only {verb} regular files");
  40     let help_msg = format!("use `{help_unary}FileType::is_dir()` instead");
  41     span_lint_and_help(cx, FILETYPE_IS_FILE, span, &lint_msg, None, &help_msg);
  42 }